I have an Intel DZ87KLT-75k based system and it was working great since it was put together until I started experiencing an odd issue about a year ago, once in a while it would power cycle before posting and then boot. Then it would power cycle more than once before it posted and booted. Then a few times it power cycled over and over for lengthy periods of time before it booted. It took about a year for the issue to slowly evolve to the point we're at now, slowly day by day getting worse and worse.

Last week if I powered the system on, it might power cycle for hours until it eventually booted up. This week it won't boot up at all, just power cycles over and over and over and won't POST.

During all of this, after the system booted it ran flawlessly. Never a blue screen or crash, video games were great, no issues at all.

Here are diagnostic details

- nothing changed between system working fine and system power cycling

- not currently overclocked, may have been a few years ago

- CPU is not overheating

- swapped out the RAM

- swapped out the power supply for a big one

- swapped out the video card with a small one

- disconnected everything but front panel header & cooling fans

- pulled CMOS battery & unplugged system for 24 hours

- tried jumpering BIOS for configuration but not getting that

- the code seen on the code POST LED during this cycle go like this (watched in slow motion)

Some of these numbers may be wrong due to how fast they flash but the dd:26, dd:44, 00:21, 00:03, and 00:10 appear long enough to be certain

I would be tremendously appreciative if anyone has any successful advice as this system was perfect for my needs, handling everything including the latest games with ease, and I'm not at all in the mood to reconfigure a new system.

Hhmmm, it seems to be falling into recovery code and this is usually as a result of a memory initialization failure. When you replaces the memory, what exactly did you replace it with? Also, did you have Fast Boot enabled?

I'm confident it isn't a memory problem as it's unlikely 2 pairs of RAM would fail at the same time; I had 4 x 8GB DDR3 which I split for testing into 2 x 8GB then 2 x 8GB and also rearranged for another permutation and same problem occurs. I then replaced it with compatible DDR3 and same problem occurs.

I may have had Fast Boot enabled but considering the BIOS was reset when the CMOS battery was pulled, it's probably not enabled now. I suppose that depends on the defaults but 'enabled' is probably not default.

No, clearing CMOS does not clear the BIOS configuration. The BIOS uses flash to store its configuration; they haven't used CMOS for BIOS configuration storage for more than 10 years. All you have lost by removing the battery is the date and time.

When we talk about memory errors, there are a number of causes. There are failures in the memory. There are failures in the memory controllers. Finally, there is noise - noise injected by the DIMMs, noise injected by the processor and noise injected by the board (and anything plugged into it). The combination of all three, if it exceeds thresholds for the noise prevention circuitry (bus terminators, etc.), can cause data errors and potential system hangs. As systems age, noise can build in all three locations. Memory that worked when the system is new can fail later on as circuitry ages. This is why I asked what memory you were using. If it is also overclocking the processor (i.e. running faster than 1600MHz), then it only increases the chances of memory errors over time. Test with other memory; swapping the DIMMs that you used all along is not a proper test.

My understanding, based on Intel's documents on the topic last updated in 2017, is that the CMOS settings are stored in a volatile location unless the user has gone out of their way to save them as the BIOS defaults.

While I'm extremely skeptical that four sticks of RAM have independently simultaneously failed, I'm curious how one can reset to BIOS defaults if there is no jumper to do that? Does settings the jumper to 'configuration' not do that as I stated was tested above?

Nope, there are zero settings stored in CMOS and there hasn't been any stored there for a very long time (barring BIOS bugs). Both current and default settings are stored in flash (along with the firmware itself).

Settings are restored to defaults from within BIOS Setup (using F9 key). There is no jumper that will reset them.

If you move the BIOS Configuration from pins 1-2 to pins 2-3, this asks the BIOS to start in Maintenance Mode, but this simply makes some additional settings and capabilities available.

If you want to have the BIOS ignore the current settings and POST with defaults (and automatically enter BIOS Setup), engage the Back-to-BIOS button on the board's back panel. Note that this doesn't affect the current BIOS configuration - at least not until you make changes and save them.

Nope, there are zero settings stored in CMOS and there hasn't been any stored there for a very long time (barring BIOS bugs). Both current and default settings are stored in flash (along with the firmware itself).

Interesting. We have some newer Asus' boards here that can be reset by pulling CMOS batteries so it seems there are variable factors that affect this. I was basing my Intel opinion on Intel's document: CMOS Battery on Intel® Desktop Boards but since Intel hasn't made desktop boards in some time, I guess it's out of date.

Thanks for that insight and also reminding me of the back to bios button on the rear of the board. I'd seen it years ago and forgot about it, even reading the manual I missed it as I was focused more on the 'top' of the motherboard.

N. Scott Pearson wrote:

If you want to have the BIOS ignore the current settings and POST with defaults (and automatically enter BIOS Setup), engage the Back-to-BIOS button on the board's back panel. Note that this doesn't affect the current BIOS configuration - at least not until you make changes and save them.

This did not work for me but the behaviour was altered slightly in Back-to-BIOS mode. The system ramps up, slows down and almost sounds like a normal boot and it does not power cycle in Back-to-BIOS mode but it also doesn't give me video or POST, no num-lock.

If I turn Back-to-BIOS off for normal mode, the original power cycling issue returns.

N. Scott Pearson wrote:

What is the speed of your DIMMs?

The SPD would have it at 1333 but the RAM is advertised overclockable to 2400. The other RAM tested probably had SPD defaults of 1866.

I'm 95% sure that the CPU and RAM were running at stock speeds for the majority of the lifespan of this system and the BIOS settings were set to standard defaults (for CPU and memory timings SPD). So any RAM compatible with this motherboard is expected to light up as the memory settings are all set to obtain via SPD.

I do have another 87 chipset system 'round here somewhere and I could swap CPUs, was just hoping to avoid that as this system has a fancy cooling system around it. But I think that's the only thing left... ?

Tested this system's i7 CPU in another 87 chipset motherboard and the CPU is fine.

Tested the working system's i5 CPU in this DZ87KLT-75k system and the same issue is experienced, no post with back-to-BIOS and power cycling trying to start normally.

Pulled the DZ87 from the board, have it on the bench with all alternative working parts (video, memory, power supply, and CPU) with nothing else connected internally outside of power and the power cycling issue still persists. It seems like the board is toast... but maybe you or someone has a hail mary suggestion as I'd like to reactivate it.

Actually, that article was many years out of date when the boards group (still) existed! I can't remember exactly where the cutover occurred, but a quick check yielded that the transition had already taken place before the 5 Series boards were released (that's as far back as I have hardware to verify).

[Aside: I asked one of the Board BIOS engineers: Why, if the CMOS isn't used, does clearing CMOS make a difference? His response was: "CMOS clear/battery pull is still used to trigger an RTC Reset that affects some chipset/ME features. Note that even the scope of RTC Reset is getting reduced over time as more designs appear with no CMOS battery!". Typical BIOS engineer response; he answered the question without telling us anything. Fact is, they don't know why it makes a difference. I blame it on bugs in the BIOS; there are still bits of legacy code with dependencies on CMOS content - even after all this time!]

I don't like the sound of your description for what it did (and didn't do) with the Back-to-BIOS button engaged. This sounds suspiciously like something has failed on the board. Still, let's not give up too soon. First, can you pull your graphics card and test with a monitor connected to the HDMI connector on the board's back panel?

Since our last exchange I discovered an issue with a stick of RAM where the 87 motherboard with my i7 CPU would intermittently not boot, similarly to the problem with my board. "Ohhh nooo...", I groaned, thinking I missed something.

However I went back and re-tested just two of the four sticks and the problem existed. I also re-re-retested another set of RAM with the i7 CPU and the problem still exists.

Thanks for taking the time to try, I certainly went further with your input than I did on my own.

My KL board is still trucking along, though I am getting occasional SMBus failures (bus lockups) while reading the temperatures from my DIMMs. I am hoping that this is just the TSOD IC in one DIMM causing this (though it is getting harder and harder to purchase non-ECC DIMMs with the TSOD feature).

Here is a report from Intel Desktop Utilities showing the sensors that I am monitoring:

I have the Intel Quiet System Technology (QST) algorithms (which are running on the Embedded Controller in the Super I/O) fully optimized so the fans will work in concert to keep the system cool and avoid raising the speed of the (loud) CPU and (ugly louder) GPU fans. Despite there being 9 fans in the system (counting the PSU and the two on my GPU), I barely hear them at all (albeit with my 60-year old ears).

I bought the version of the DIMMs with TSOD feature but not LEDs. As I said, I have one DIMM that is (I think) causing the SMBus to lock up. I just talked to Crucial. They are telling me that the Ballistic Elite and Ballistic Tactical lines still have temperature sensors included, so I can still get some that have sensors but do not have the LEDs. They warned me, however, that this memory is very finicky and that I would need to replace a pair of DIMMs, not just the bad one...